Q: I got a number of daylight saving time story pitches from sleep specialists this year. Is an hour time change twice a year that big a deal? Aren't most people just tired that day and fall asleep an hour earlier the next night?

A: Well, there is a higher incidence of workplace and occupational accidents, particularly in industries like mining and transportation, for about two to three weeks right around this time. The time change can also have a negative impact on scholastic performance, as with teenagers taking tests during this two-week period. Beyond that, your characterization is fairly accurate. Most people adjust in a couple days — some, obviously, better than others.

Q: Aren't there studies that suicides and heart attacks increase mildly in the first days after the spring change and decrease mildly after the autumn change?

A: Yes, there is some data supporting that. Those are epidemiological studies — they don't show cause and effect in any way. Researchers just plot out heart attacks for the year and find an increase after clocks are moved up.

Q: What actually happens in the brain to cause difficulty adjusting to time changes?

A: Losing an hour of sleep contributes to sleep debt. If you don't make up the debt, it manifests in waking up tired, needing a lot of caffeine to get going, nodding off during the day. There are also more subtle signs — irritability, depression, attention deficit, inability to focus, inability to multi-task, anxiety.

The second issue is light. The body clock that tells us when to go to sleep and when to wake up is influenced by light and the hormone melatonin. When melatonin levels go up, the body clock tells the brain to go to sleep. When bright light shines, melatonin production shuts down and the brain tells the body to wake up and be alert. At daylight saving time, it takes a little while for the body clock to readjust melatonin activity.

A: I think society is probably less tolerant because we've become so sleep-deprived. The average amount of sleep Americans get is now well below seven hours, even less for teenagers, who require nearly nine hours of sleep. I think medical professionals are starting to take daylight saving time more seriously — certainly, we give our patients additional counseling because of it.

Q: I know you emphasize going to bed a little earlier each night as a preventative, but since people won't be reading this until after the change, are there any after-the-fact adjustment strategies you suggest?

A: In the morning, getting bright light is really the key — for people who have trouble getting going in the morning, commercial light boxes are available. Also, 20 minutes of good aerobic exercise will get the adrenalin pumping, a great natural alerting influence on the body. At night, limiting exposure to light is important, though that's easier said than done because things like laptops and LCD television screens emit light that's particularly alerting to one's body clock. Snacks rich in tryptophan — milk, bananas, almonds, pistachios — are also a good idea.

Q: How does a time change like this affect people with insomnia?

A: Paradoxically, those patients are kind of just used to having poor sleep all the time — they're already sleeping one to three hours a night and using sleeping pills — so it may not have too much of an effect. Those for whom it does have an effect is when it's related to a body clock disturbance, such as an older teenager who can't get to sleep until 4 a.m.